Typical x-ray tubes and x-ray devices (device containing x-ray tubes) have been known and used for some time. Unfortunately, they are usually bulky and are powered by heavy, high-voltage power supplies that restrict mobility. As well, they are often difficult and time-consuming to use. In many instances, a sample for analysis must be sent to an off-site laboratory for analysis by the x-ray device.
These limitations can be very inconvenient for many popular uses of x-ray devices containing them. Such uses include x-ray fluorescence (XRF) of soil, water, metals, ores, well bores, etc., as well as diffraction and plating thickness measurements. Typical x-ray imaging applications require the sample to be imaged to be brought to the x-ray device. These limitations have led to an increased interest in making x-ray devices portable. See, for example, U.S. Pat. Nos. 6,661,876, 6,459,767, 6,038,287, and 6,205,200; U.S. Published Patent Applications 2003/0048877, 2003/0002627, and 2003/0142788; and European Patent Nos. EP0946082, EP0524064, EP0247758, EP0784965, and EP0488991; the entire disclosures of which are incorporated herein by reference.
Many of these existing designs increase the portability of x-ray devices. At the same time, however, these designs are limited for several reasons. First, most of the designs are not truly portable since they have an external power source (i.e., require utility-supplied line voltage). Second, while some of the portable designs, especially the XRF systems, have internal or “integrated” power supplies, they don't have the high x-ray tube current load that is often necessary for x-ray imaging. For example, energy-dispersive XRF typically requires x-ray beam currents of less than 1 milliampere while x-ray imaging typically requires greater than about 2 milliamperes. Finally, the radiation shielding for the x-ray tubes usually comprises lead, which is quite heavy and limits the portability of the device.
A further limitation on design of the increased portability is the image display components. High-quality imaging displays for displaying the results of the x-ray analysis are difficult to integrate into the design of the housing of the portable x-ray device. Consequently, many of the portable designs have the image display component external to the chassis or housing containing the x-ray tube.